1. Field
The present invention generally relates to wireless communication networks that provide multi-user (“shared”) forward-link broadcast upon various broadcast channels. More particularly, under circumstances where a mobile station that is receiving broadcast content additionally receives or places a point-to-point call, the invention concerns operations to appropriately manage the point-to-point call and/or the broadcast connection.
2. Background
Many known communication systems transmit information signals from an origination station to a physically distinct destination station. The information signal is first converted into a form suitable for efficient transmission over the communication channel. Conversion, or modulation, of the information signal involves varying a parameter of a carrier wave in accordance with the information signal in such a way that the spectrum of the resulting modulated carrier is confined within the communication channel bandwidth. At the destination station the original information signal is replicated from the modulated carrier wave received over the communication channel. Such a replication is generally achieved by using an inverse of the modulation process employed by the origination station.
Modulation also facilitates multiple-access, that is, simultaneous transmission and/or reception, of several signals over a common communication channel. Multiple-access communication systems often include a plurality of subscriber units requiring intermittent service of relatively short duration rather than continuous access to the common communication channel. Several multiple-access techniques are known in the art, such as time division multiple-access (TDMA), frequency division multiple-access (FDMA), amplitude modulation multiple access (AM), and code division multiple-access (CDMA) spread spectrum. Multiple-access communication systems may be wireless or wireline and may carry voice and/or data.
In a two-way, multiple-access wireless communication system, communications between users are conducted through one or more base stations. In one example, one user on a first wireless mobile station communicates with another user on a second wireless mobile station by transmitting data on a reverse link to a base station. The base station receives the data and, if necessary, routes the data to another base station. Ultimately, the data is transmitted on a forward link of the final base station to the second mobile station. “Forward” link refers to transmission from a base station to a wireless mobile station and the “reverse” link refers to transmission from a wireless mobile station to a base station. In many communication systems, the forward link and the reverse link utilize separate frequencies.
Communications can also be conducted between one user on a wireless mobile station and another user on a landline station. In this case, a base station receives the data from the mobile station on a reverse link, and routes the data through a public switched telephone network (PSTN) to the landline station. Communications also occur in the opposite direction.
The foregoing wireless communication services are examples of “point-to-point” communication service. In contrast, “broadcast” services deliver information from a central station to multiple mobile stations (“multipoint”). The basic model of a broadcast system consists of a broadcast net of users served by one or more central stations, which transmit news, movies, sports, or other “content” to the users. Here, each mobile station monitors a common broadcast forward link signal. Because the central station fixedly determines the content, the users do not generally communicate back. Examples of common usage of broadcast services communication systems are television, radio, and the like. Such communication systems are generally highly specialized.
With recent advancements in wireless telephone systems, there has been growing interest in using the existing, chiefly point-to-point wireless telephone infrastructure to additionally deliver broadcast services. In this respect, a number of important advances have been made by QUALCOMM CORPORATION of San Diego, Calif. The following references describe various QUALCOMM advances relating to the use of shared communications channels to deliver broadcast content in a wireless telephone network. U.S. Pat. No. 6,980,820, issued Dec. 27, 2005, and entitled “METHOD AND APPARATUS FOR SIGNALLING IN BROADCAST COMMUNICATIONS SYSTEM.” U.S. Patent Publication No. 2004/0131075 published Jul. 8, 2004 and entitled “METHOD AND SYSTEM FOR MULTICAST SERVICE INITIATION IN A COMMUNICATION SYSTEM.” U.S. Patent Publication No. 2003/0035389, published Feb. 20, 2003 and entitled “METHOD AND SYSTEM FOR UTILIZATION OF AN OUTER DECODER IN A BROADCAST SERVICES COMMUNICATIONS SYSTEM.” U.S. Patent Publication No. 2003/0228861 published Dec. 11, 2003 and entitled “METHOD AND APPARATUS FOR OVERHEAD MESSAGING IN A WIRELESS COMMUNICATION SYSTEM.” U.S. Patent Publication No. 2004/0203655, published Oct. 14, 2004 and entitled “METHOD AND APPARATUS FOR COMMENCING SHARED OR INDIVIDUAL TRANSMISSION OF BROADCAST CONTENT IN A WIRELESS TELEPHONE NETWORK.” U.S. Patent Publication No. 2004/0203336, published Oct. 14, 2004 and entitled “METHOD AND APPARATUS FOR SWITCHING BETWEEN SHARED AND INDIVIDUAL CHANNELS TO PROVIDE BROADCAST CONTENT SERVICES IN A WIRELESS TELEPHONE NETWORK.” The foregoing references are incorporated by reference into the present disclosure.
Although the foregoing applications are satisfactory in many respects, one aspect of wireless broadcast systems that has not been fully developed is the initiation of point-to-point calls involving wireless mobile stations that are already receiving shared broadcast service.